Humanoid Robotic Manipulation Benchmarking and Bimanual Manipulation Workspace Analysis

The growing adoption of robots for new applications has led to the use of robots in human environments for human-like tasks, applications well-suited to humanoid robots as they are designed to move like a human and operate in similar environments. However, a user must decide which robot and control algorithm is best suited to the task, motivating the need for standardized performance comparison through benchmarking. Typical humanoid robotic scenarios in many household and industrial tasks involve manipulation of objects with two hands, bimanual manipulation. Understanding how these can be performed in the humanoid’s workspace is especially challenging due to the highly constrained nature due to grasp and stability requirements, but very important for introducing humanoid robots into human environments for human-like tasks. The first topic this thesis focuses on is benchmarking manipulation for humanoid robotics. The evaluation of humanoid manipulation can be considered for whole-body manipulation, manipulation while standing and remaining balanced, or loco-manipulation, taking steps during manipulation. As part of the EUROBENCH project, which aims to develop a unified benchmarking framework for robotic systems performing locomotion tasks, benchmarks for whole-body manipulation and loco-manipulation are proposed consisting of standardized test beds, comprehensive experimental protocols, and insightful key performance indicators. For each of these benchmarks, partial initial benchmarks are performed to begin evaluating the difference in performance of the University of Waterloo’s REEM- C, “Seven”, using two different motion generation and control strategies. These partial benchmarks showed trade-offs in speed and efficiency for placement accuracy. The second topic of interest is bimanual manipulation workspace analysis of humanoid robots. To evaluate the ability of a humanoid robot to bimanually manipulate a box while remaining balanced, a new metric for combined manipulability-stability is developed based on the volume of the manipulability ellipsoid and the distance of the capture point from the edge of the support polygon. Using this metric, visualizations of the workspace are performed for the following scenarios: when the center of mass of the humanoid has a velocity, manipulating objects of different size and mass, and manipulating objects using various grips. To examine bimanual manipulation with different fixed grasps the manipulation of two different boxes, a broom and a rolling pin are visualized to see how grip affects the feasibility and manipulability-stability quality of a task. Visualizations of REEM-C and TALOS are also performed for a general workspace and a box manipulation task to compare their workspaces as they have different kinematic structures. These visualizations provide a better understanding of how manipulability and stability are impacted in a bimanual manipulation scenario

TextDeformer: Geometry Manipulation using Text Guidance

We present a technique for automatically producing a deformation of an input triangle mesh, guided solely by a text prompt. Our framework is capable of deformations that produce both large, low-frequency shape changes, and small high-frequency details. Our framework relies on differentiable rendering to connect geometry to powerful pre-trained image encoders, such as CLIP and DINO. Notably, updating mesh geometry by taking gradient steps through differentiable rendering is notoriously challenging, commonly resulting in deformed meshes with significant artifacts. These difficulties are amplified by noisy and inconsistent gradients from CLIP. To overcome this limitation, we opt to represent our mesh deformation through Jacobians, which updates deformations in a global, smooth manner (rather than locally-sub-optimal steps). Our key observation is that Jacobians are a representation that favors smoother, large deformations, leading to a global relation between vertices and pixels, and avoiding localized noisy gradients. Additionally, to ensure the resulting shape is coherent from all 3D viewpoints, we encourage the deep features computed on the 2D encoding of the rendering to be consistent for a given vertex from all viewpoints. We demonstrate that our method is capable of smoothly-deforming a wide variety of source mesh and target text prompts, achieving both large modifications to, e.g., body proportions of animals, as well as adding fine semantic details, such as shoe laces on an army boot and fine details of a face

Exploring the effects of swirl intensity on NO emission in ammonia-methane-air premixed swirling flames

The high emission of nitrogen oxides (NOx) is one of the major obstacles to the practical application of ammonia as a carbon-free fuel. Improving the flow distribution and structure has been demonstrated to achieve low NOx emissions. However, in comparison to hydrocarbon flames, the influence of swirl intensities on ammonia NOx emissions is still not well understood. This study builds upon previous research by further exploring the effects of swirl intensity on NO production in ammonia-methane-air premixed swirling flames. A new adjustable axial swirler was designed to achieve a wide range of swirl numbers. We measured flame morphology, NO emissions, and NO and OH planar laser-induced fluorescence (PLIF) images over extensive ranges of equivalence ratio and ammonia fraction. The study found that increasing the swirl number from 0.6 to 1.0 resulted in a more compact flame, with enhanced reactions in the corner recirculation zone. Varying the swirl number significantly alters the NO concentration in the exhaust gas. The concentration of NO was significantly reduced at an equivalence ratio of 0.90 and an ammonia fraction greater than 80%. NO/OH-PLIF indicated that NO was primarily formed in the main reaction zone, with NO-PLIF intensity in the post-flame zone almost remaining constant at different heights. The integrated intensities of NO and OH-PLIF were obtained at different heights above the nozzle. A positive linear correlation was observed between NO-PLIF plateau intensity and NO mole fraction. The increased heat loss to the wall at larger swirl intensities reduces the flame temperature in the main reaction zone, which inhibit the formation of OH radicals, ultimately resulting in low NO emissions

Bio accessibility of tire-associated organic chemicals in fish gut (Oncorhynchus mykiss): insights from an in vitro digestion model

Tire and Road Wear Particles (TRWP) account for an important part of the anthropogenic particles released into the environment. There are scientific knowledge gaps as to the potential bio accessibility of chemicals associated with TRWP to aquatic organisms. This study aimed to investigate the solubilization of five tire-associated chemicals into fish gut using an in vitro digestion model (Oncorhynchus mykiss). Our results show that the targeted compounds were partly and rapidly solubilized into simulated fluids (SF) present in the gastrointestinal tract within a typical gut transit time for fish (3h in SFGASTRIC and 24h in SFINTESTINAL). The effects of food co-ingestion on the solubilization of tire-associated chemicals was compound-specific and either lowered or stimulated their solubilization into the gut fluids. Therefore, the uptake of the tire associated chemicals by the epithelial cells and related toxicity to fish need to be investigated

Diatom beta-diversity in streams increases with spatial scale and decreases with nutrient enrichment across regional to sub-continental scales

Aim To quantify the relative contributions of local community assembly processes versus gamma-diversity to beta-diversity, and to assess how spatial scale and anthropogenic disturbance (i.e. nutrient enrichment) interact to dictate which driver dominates. Location France and the United States. Time period 1993-2011. Major taxa studied Freshwater stream diatoms. Methods beta-diversity along a nutrient enrichment gradient was examined across multiple spatial scales. beta-diversity was estimated using multi-site Sorensen dissimilarity. We assessed the relative importance of specialists versus generalists using Friedley coefficient, and the contribution of local community assembly versus gamma-diversity to beta-diversity across spatial scales, with a null model. Finally, we estimated the response of beta-diversity to environmental and spatial factors by testing the correlations between community, environmental and geographical distance matrices with partial Mantel tests. Results beta-diversity generally increased with spatial scale but the rate of increase depended on nutrient enrichment level. beta-diversity decreased significantly with increasing nutrient enrichment level due to the loss of specialist species. Local assembly was an important driver of beta-diversity especially under low nutrient enrichment. Significant partial Mantel correlations were observed between diatom beta-diversity and pure environmental distances under these conditions, highlighting the role of species sorting in local assembly processes. Conversely, in heavily enriched sites, only spatial distances were significantly correlated with beta-diversity, which indicated a substantial role of dispersal processes. Main conclusions Nutrient concentration mediated the expected increase in beta-diversity with spatial scales. Across spatial scales, beta-diversity was more influenced by local assembly processes rather than by gamma-diversity. Nutrient enrichment was associated with an overall decline in diatom beta-diversity and a shift in assembly processes from species sorting to dispersal, notably due to the elimination of some specialists and their subsequent replacement by generalists.Peer reviewe

Biogeographical Patterns of Species Richness and Abundance Distribution in Stream Diatoms Are Driven by Climate and Water Chemistry

In this intercontinental study of stream diatoms, we asked three important but still unresolved ecological questions: (1) What factors drive the biogeography of species richness and species abundance distribution (SAD)? (2) Are climate-related hypotheses, which have dominated the research on the latitudinal and altitudinal diversity gradients, adequate in explaining spatial biotic variability? and (3) Is the SAD response to the environment independent of richness? We tested a number of climatic theories and hypotheses (i.e., the species-energy theory, the metabolic theory, the energy variability hypothesis, and the climatic tolerance hypothesis) but found no support for any of these concepts, as the relationships of richness with explanatory variables were nonexistent, weak, or unexpected. Instead, we demonstrated that diatom richness and SAD evenness generally increased with temperature seasonality and at mid- to high total phosphorus concentrations. The spatial patterns of diatom richness and the SADmainly longitudinal in the United States but latitudinal in Finlandwere defined primarily by the covariance of climate and water chemistry with space. The SAD was not entirely controlled by richness, emphasizing its utility for ecological research. Thus, we found support for the operation of both climate and water chemistry mechanisms in structuring diatom communities, which underscores their complex response to the environment and the necessity for novel predictive frameworks.Peer reviewe